Process of making safety-treads



G. N. .IEPPSON.

PROCESS 0F MAKING SAFETY TREADS. APPLzcATloN FILED FEB.14, 1919.

Patented Mar. 15, 1921.

INVENTOR ATT UNITED STATES PATENT;- omer..

GEORGE N. JEPPsoN, or WORCESTER, MASSACHUSETTS, AssreNoE To NORTON COMPANY, 0E WORCESTER, MASSACHUSETTS, A CoEPoEATIoNoF MASSA- PROCESS OF MAKING SAFETY-TREADS.

i Specification of Letters Patent.

Patented Mar. 15, 1921,

which should be found in a good road. It

Should beeconomical as to first cost and maintenance. It should be'fadapted to the grade and suited to the particular tralic or wear for which it is intended. Ift should be sub;

stantially impervious" to' moisture, and ofv such nature that it will notbe injured by Climatic and temperature changes. It should be smooth surfaced, dustless, mudless and easily cleaned. It should be hard, tough, durable and resi-stant to crushingyabrasion and disintegration under pedestrian and traiiic wear. Most essential of all, it Should give a good foothold: to ,pedestrians and horses and be anti-slipping to motorvvehicles to prevent accidents.

It is-well known that asphalt, concrete 4 and wooden pavements and surfaces covered with tar or various bituminous preparations are slippery when wet or dirty. It is customary-to Sprinkle sand or Similar antislipping materials on `such roads, but the v loose rains'tend to wear out the surfacing and are objectionable. The more durable pavements of blocks of granite or similar stones wear Adown to a smooth polished surface and so become slipperyespecially in damp weather when there isa scum of grease or moisturepresent.A The less slippery pavements of earth and gravel are of course short lived and are not suitable for heavy traiiic.

It is accordingly an obj ect of my invention to overcome these' diiculties and to provide a tread particularly adapted for roads which always presents 4an anti-slipping and -yet a hard and durable surface capableof resisting traffic wear and -abrasions for a long period of time. A furtherobject is to pro` vide a Simple and economical process :o making the antifslipping material and 1ncorporating it in a tread.

' of 36 mesh and finer.

VVithfthese and other objects in -vieW as will be apparent from the following disclosure, my invention resides in the construction and the steps of a process set forth in the accompanying specification and covered by the claims appended hereto.

It has been proposed to incorporate silicon carbid grains in a concrete road by mixing the gram with the cement material. Owing to the poor bonding qualities of cement and the fact that silicon carbid fractures and crumbles away easily, these hard grains will not be retained for any length of time in the road surface, and consequently will not serve as an anti-slipping and wear-resisting material. On the other hand, crystalline material of a hardness of 9 or more on Mohs scale possesses excellent anti-slipping qualities and I have found a way in which'su-ch materials may be utilized in road construction.

In accordance with my invention, I bond together into la unitary mass'or conglomerfate a large number'of grains of crystalline alumina such as corundum, emery, electric ally fusedalumina etc., which may contain various impurities, or silicon carbid, or Similar substances, preferably of a hardness of 9 or`more, which have large anti-slipping and wear-resistingqualities; and I use such a bonded mass asI a slip-proof aggregate for, embedding in a suitable cementing material to form a compound conglomerate adapted for a tread or pavement. These hard materials, ordinarily obtainable in large'masses, are crushed. to form small grains. of desired sizes, it being found preferable to use grains In order that the aggregate may have the desired qualities, -I utilize a bond for the crystals, which ,will hold the grains in place almostA indefinitely, which will resist the abrasione, strains and impacts of traflic and pedestrian wear without breaking or permitting the grains to become loose in their settings and which will` form an exceedingly hard mass, preferably of irregular shape and -large surface area, capable of firmly uniting with cementitious tread or roadbuilding material. Of the various available materials, `I prefer to use bonds well known in the ceramlc art, which vitrify or become glassy at kiln temperatures. Depending upon the nature of these bond mixtures, the

proportions of the ingredients and their treatment, one may obtain either soft or hard vitrilied or glassy products. As an illustration of a bond adapted to form an artificial stone substantially as hard as trap rock a ceramic clay material of the following composi'tionmay be utilized:

SlipV clay 44 parts by weigh-t Feldspar -44 parts by weight Ball clay 12 parts by weight ening the mass withwater sul'liciently to form it by the dry press process into lumps or shapes of convenient size. I find it desirable in certain instances to form these shapes in an auger type brick machine.

These lumps, which are preferably made asy briquets of a given size and shape in order that the product obtained from the kiln may 4be uniform in nature,are burned or heatedl in a tunnel or other `variety of kiln for a suitable time and under a degree of heat Whichdepends mainly on the nature of the bond, the temperature, the size of the kiln and the size and shape of the lumps. This firing operation is carried on until the bond is vitrified, it ordinarily consuming from 50 to 100 hours at a temperature approximating 1300o centigrade when a slowly burned product is desired. The hard burned mass is then cooled slowly'for a suitable length of time and thereafter reduced to the required sizes, as for example by being broken by Vrolls or in a rock crusher to form irregularly shaped pieces or aggregate of suitable sizes, ordinarily ranging from -linch in thickness to -2 inches, depending upon the character of Wear to which the material will be exposed.

In order to form a Wear-resisting tread surface capable of use for` pedestrian Wear` or as a road I form a compound conglomerate by incorporating these conglomerate chips or shapes in a suitable bond or cementitious medium capable of holding them in place when subjected to the desired use. As a specific example of the application of my invention to pavement constructions, reference is to be had to the accompanying drawing showing a section in perspective 4of a concrete road having a slip-proof surface layer thereon.

To provide a foundation for such a road surfacing, one may excavate suicient material from the roadbed to remove the surface soil, decaying matter and similar substances and preferably to reach a satisfactory base material. This sub-grade 5 is formed to the proper grade and cross section and is thor-A oughly compacted as by rolling to a firm and even surface, the various depressions and unevennesses in the grade being leveled Y off during the operation. The curbstones 10 may be then putin place and the necessary steps taken to provide forl gutters, expansion joints, wire netting reinforcements etc. If as illustrated, the foundation material Aconsists of concrete, various well known methods of making the saine may be vadopted. One type of road may be made by first putting down a layer 15 of crushed stone of a tough material of good binding properties, such as trap or granite, although such materials as limestone, mica schist, quartz, etc.,

may be used, depending largely upon what so is available in the immediate vicinity. This crushed stone should be thoroughly rolledl under heavy pressure until the stones are wedged or interlocked in place. While such a base layer l5 may. be omitted and the concrete road laid on the sub-grade it is considered that this provides drainage for water absorbed by the road, and so is desirable.

It, of course, is obvious that various other,

water, may be spread over this rolled stone` surface and brushed as much as possible into the interstices between the aggregate, after which the mass may be again rolled if desired. Another layer'of crushed rock may .be then rolled in place and a. further application of grout made, this being continued until the foundation is of vsufficient thickness for standing the strains of traffic. If desired' the rock may be mixed with the cement, sand and water in an ordinary concrete mixer and laid in place as one or'moreV layers. The proportions of the ingredients may be varied as is well known in the art.

In order to make this concrete road antislipping, I provide a top surfacing 25 comprising my ceramic bonded chips suitably embedded in a cementitiousl matrix to form a conglomerate. This matrix may comprise various substances suitable for roads, such as hydraulic cement, asphalt or tar preparations, depending upon the typeof road desired. If the surface is for pedestrian Wear, such cements as magnesium oxychlorid, resinous or bituminous bonds may be used depending upon the degree of exposure to the weather, the nature, of the frictional Wear, the stresses, etc., to which the tread will be subjected.- If Portland cement is'used, the top layer is preferably laid before the conlaying this top dressing 25. For example,

the concrete aggregate should be mixed preferably for two or three minutes -and poured upon the foundation before the mortar filling beneath it has set and then be tamped .until the aggregate has assumed a stable position and a slight 'surfacing of water is noted. If desired, one may roll the i anti-slipping aggregate into place on the top of the concrete foundation, and, then grout .it with a suitable cement mortar. .One or more layers may be laid in 'this way, depending upon the amountv of traffic to which the material will be subjected, the lower one being thorou hly /ramme'd into the concrete.' It is advisa le, however, that the total layer 25 beat least 2 thic'k. In certain rsases, a layer of smaller trap rock may be placed on the foundation layer and thoroughly rammed into the concrete foundation to insure good contact, then a top layer contain ing the anti-slipping aggregate be applied immediately, thoroughly compacted and then trowled or shaped to conform to the grade and cross section of the street. When sufficiently hard the surface may be fioated and steelftroweled and the depressions filled. If it is desired to incorporate these. antislipping fragments or aggregates with asphaltum the two may be mixed together while the asphaltum is hot and-the same applied to a' suitable foundation in the manner in which asphaltum is now laid.

The size of these anti-slipping pieces may obviously be varied depending upon the type of surface desired for the road. As illustrated in the drawing, the aggregate may average smaller than the trap rock below it.` By utilizing aggregates comprising the run of the mill which will pass through a 2 ring, but preferably omitting the extremely fine sizes, one may obtain a road surface which may be compacted to a good anti-slipping surface suitable forl heavy traiiic. This mixture may be made up in suchproportions that the cement will fill the voids-between the aggregate when laid with a slight excess of mortar left over.

On the other hand, the aggregates should be of such sizes and in such proportions as to constitute the `major portion of the tread surface, so as to receive the traffic wear and protect the cement or outer bond from. unusual abrasions. Due tothe extensive surface of these fragments and/ the fact that they are ,porous and have numerous fine projections on the surface, they unite very firmly with the cement and so do not become easily dislodged from the face of the road.

` In accordance with this invention, I have u provided a compound conglomerate comprising a cement body having embedded therein an irregularly shaped, rough surfaced, `antislipping conglomerate of crystalline grainsl of a hardness of 9 or more unitarily bonded, preferably by a ceramic clay material vitried or rendered glassy in a ceramic high temperature kiln.

What I claim is t l; The process of makinga safety tread comprising bonding anti-slipping grains of extreme hardness with a material capable of forming a hard, wear-resisting mass and bonding pieces of said conglomerate mass with acementitious tread magma to form a compound conglomerate in which-said pieces are adapted to receive the tread wear.

2. The process of 'makinJ an anti-slipping tread comprising bonding hard, antislipping grains by means of a ceramic material capable of forming a wear-resisting mass and forming a compound conglomerate of these bodies with a cementitious mass in which the bonded grains are adapted to receive the tread wear.

, 3. The process of making an anti-slipping tread comprising bonding small crystalline grains of ahardness of 9 or more with a vitrified ceramic bonding material and embedding these bodies irregularly in a pound conglomerate in which the bonded grains constitute the major portion of the tread surface. v

4. The process of making a tread comprising bonding hard, anti-slipping crystalpound conglomerate in'which the fragments serve to receive the larger proportionr ofthe tread wear.

5. The process of makmg an anti-slipstoneforming medium to provide a comping, wear-resisting tread comprising the steps of bonding small crystallinel grains of a hardness ofv 9 or more with a vitrified ceramic material to form a wear-resisting, anti-slipping conglomerate mass, crushing this mass into irregularly shaped pieces of conglomerate and bonding said pieces in a cementitious body to form a compoundconlglomerate in which the ceramic bonded grains receive the traic wear. ,v

6. The process of making a tread comprising bonding crystalline alumina grains with bonding material capable of' forming a wear-resisting stone-like ass, and embedJ ding small pieces of this con lomerate mass irregularly in a cement to form a compound conglomerate suitable for use as a tread surface.

7. The process of making an anti-slipping tread comprising bonding crystalline alumina grains With a ceramic bonding material 4into an irregularly surfaced porous mass and embedding chipsl of the bonded material in cement to form a tread in which the chips form the major portion of the wear-receiving surface.

8. The process of making a tread comprising mixing crystalline alumina grains 'slipping'pieces irregularly spaced therein which is capable of resisting Wear and preventing slipping thereon.

9. The process of making anti-slipping material comprising bonding hard, antislipping grains with a material capable of forming therewith a hard, Wear-resisting the grains into a hard Wear-resisting mass,

shaping the same, burning the shapes in a ceramic kiln and producing Vitrified masses;

and crushing the vitried masses into aggregatesof varying sizes containing a plurality of crystalline grains which form rough, irregular surfaces capable of being anti-slipping. i i

l1. The process of making an anti-slipping tread comprising crushing crystalline alumina into small grains, mixing these grains with vitriiiable ceramic ,materiah forming this mixture into shapes adapted for burning, subjecting the shapes to prolonged heatat a temperature capable of vitrifying the bond, cooling the mass and crushing it to produce fragments each having a plurality of grains therein for embedding in a cement to form a compound conglomerateadapted to Serve as a tread surface.

Signed at lVorcester, Massachusetts, this 13th day 0f Feb., 1919.

f GEORGE N. JEPPSON. 

